The present invention relates generally to septic systems, and more particularly to a leaching or drainage system for a septic system which uses lightweight, molded gallery structures to form a leaching field that facilitates distribution of effluent and particles, which gallery structures are provided with a maximized surface area to promote the growth of various desirable microorganisms.
In terms of volume, most of the water used in households around the United States is employed to carry off wastes, most of these wastes being organic and inorganic solids. Larger volumes of water are used for washing dishes, bathing and flushing the toilet than for drinking, cooking, washing cars, etc.
In urban areas, wastes carried by water from kitchens, bathrooms and laundry rooms are collected in a sewer system and transported to central sewage treatment plants. In rural areas and in unsewered suburban residential areas, individual septic systems are used to treat household waste. There are millions of such septic systems presently in use and being built in the United States. If properly designed, installed and adequately maintained, such a septic system will serve a household satisfactorily to treat household wastes.
In use, a septic system will condition household water carrying dirt, detergents, discarded food scraps and body wastes so that water may be readily percolated into the sub-soil of the surrounding ground. A typical septic system is comprised of a rectangular precast cement septic tank buried in the ground having a leaching or drain field extending therefrom. Household wastes or sewage flows to the septic tank under the influence of gravity from the house via a sewer line or pipe. The septic tank is a large, watertight and light-tight container in which the organic solids found in the sewage are decomposed by natural bacterial processes. Once the sewage is introduced into the tank, large solid particles sink, forming a sludge at the bottom of the tank while smaller, lighter particles as well as oils and greases rise to the surface forming a scum layer over a volume of liquid material located between the sludge and scum layers. Bacteria and other microorganisms in the tank break down and reduce the volume of the solids and scum. The bacteria cannot attack some of the material introduced into the system such as stone particles, plastic, etc. and these materials must be removed from the tank by periodic tank cleanings.
An outlet pipe is provided in the tank permitting some of the liquid material known as effluent to flow via hydrostatic pressure from the tank. The effluent still contains some decomposed solids as well as bacteria and other microorganisms found in the tank and flows into an adjoining leaching or drain field where it must be permitted to percolate through the surrounding ground.
The leaching field has traditionally been a trench in the ground about eighteen inches wide filled with gravel. A four inch perforated pipe is located in the trench surrounded by the gravel. Laid over the gravel and the pipe is a layer of tar paper, salt hay or woven plastic cloth with a layer of top soil placed thereover. The pipe is set at an appropriate pitch to permit a desired flow of the effluent therealong under the influence of gravity. In use, the effluent runs down the perforated pipe from one end of the pipe to the other and flows out the apertures therein into the surrounding gravel and eventually into the surrounding ground.
Another type of leaching field is formed of precast concrete galleries which create space underground within a gravel bed to increase the volume of the field. These galleries are made in different shapes (rectangular, triangular) and are ideal for situations where there is insufficient area for the traditional pipe and gravel systems.
Some of the drawbacks of the traditional septic systems are that the septic tanks and leaching galleries have been made from precast concrete and are extremely heavy requiring heavy construction equipment to put them in place. In the leaching fields, the gravel used in constructing them is difficult to work with and expensive. It also tends to settle and reduces the overall volume of the trench by as much as 75%.
Attempts have been made to overcome the limitations that are attendant upon the use of traditional septic systems. U.S. Pat. No. 5,087,151 to DiTulio (xe2x80x9cthe ""151 patentxe2x80x9d), which represents one such attempt, discloses a drainage and leaching field system comprising vacuum-molded polyethylene galleries that are designed to be connected and locked together in an end-to-end fashion. The galleries comprise a series of pre-molded polyethylene bodies with an arch-shaped configuration having upstanding ribs running transverse to the length of the gallery. The ribs provide compressive strength to the gallery so as to inhibit crushing of the gallery by the weight of earth under which it is buried, as well as the weight of persons, vehicles, etc. which pass over the buried gallery.
While the drainage and leaching field system disclosed in the ""151 patent provides numerous benefits over traditional systems, including the provision of a lightweight, easy to install and structurally sound system, the system disclosed in the ""151 has been improved upon, which improvements form the basis of the present invention. More specifically, it has been recognized that the beneficial decomposition of waste materials does not immediately end when effluent leaves the septic tank. Rather, when the effluent leaves the tank and flows into the adjoining leaching or drain field it still contains some decomposed solids as well as bacteria and other microorganisms found in the tank. Thus, beneficial decomposition can continue to take place in the leaching or drain field before the effluent percolates through the surrounding ground. For this reason, it would be desirable to promote the growth and flourishing of the bacteria and other microorganisms entering the leaching or drain field.
While the beneficial bacteria and other microorganisms may be free-floating in the effluent as it leaves the tank, they typically thrive when attached to a surface. As such, it has been recognized that the greater the area of surfaces provided within the leaching or drain field to which the bacteria and other microorganisms can attach themselves, the greater the number of thriving bacteria and microorganisms that can be maintained. Even though the ""151 patent discloses a series of galleries, each of which includes a plurality upstanding reinforcing ribs running transverse to the length thereof, which arrangement does provide a somewhat large surface area for accommodating bacteria and other microorganisms, an even larger surface area would be even more desirable.
What is desired, therefore, is a leaching field system which employs lightweight vacuum-molded polyethylene gallery structures to form the leaching field, which may be readily and economically fabricated and will enjoy a long life in operation, which is resistant to being crushed by weight above it, which promotes the growth and flourishing of the bacteria and other microorganisms entering the leaching field, and which is provided with a maximized surface area to so promote the growth and flourishing of the bacteria and other microorganisms.
Accordingly, it is an object of the present invention to provide a leaching field system which employs lightweight vacuum-molded polyethylene gallery structures to form the leaching field.
Another object of the present invention is to provide a leaching field system having the above characteristics and which may be readily and economically fabricated and will enjoy a long life in operation.
A further object of the present invention is to provide a leaching field system having the above characteristics and which is resistant to being crushed by weight above it.
Still another object of the present invention is to provide a leaching field system having the above characteristics and which promotes the growth and flourishing of the bacteria and other microorganisms entering the leaching field.
Yet a further object of the present invention is to provide a leaching field system having the above characteristics and which is provided with a maximized surface area to so promote the growth and flourishing of the bacteria and other microorganisms.
These and other objects of the present invention are achieved by provision of a gallery for guiding liquid through a leaching or drain field and allowing liquid to seep into adjacent ground. The gallery includes an elongated main body portion having an undulating wall defined by a plurality of laterally spaced apart ribs, the undulating wall defining an outer surface and an interior space for liquid and particles to flow therethrough. A plurality of area enhancing elements are formed on the outer surface of the undulating wall for increasing a surface area of the outer surface to promote the growth and flourishing of the bacteria and other microorganisms on the outer surface.
The undulating wall of the gallery preferably has a plurality of holes passing therethrough for allowing liquid and particles to escape from the interior space into the leaching or drain field. The area enhancing elements may comprise protuberances, dimples, surface texturing or a combination of two or more of such elements. Moreover, the area enhancing elements may comprise regular geometric shapes, such hemispherical, semispherical, polyhedral, conical and/or frustoconical shapes, or may comprise irregular shapes. Furthermore, the area enhancing elements may all be of substantially the same size or may be randomly sized, and may be regularly or randomly spaced.
In another aspect, a method for creating such an above-described gallery is provided.